EXERCISE LEGEND
02

Nutrition · Mifflin–St Jeor BMR

Calories & Macros

Estimate daily calories and a protein/fat/carb split for your bodyweight and goal, with the DRI limits enforced.

Sex
Units
Goal

Daily target · Maintain

2,798kcal

At your TDEE · moderately active. An estimate — population equations miss individuals by around 10% either way.

Energy budget

BMR (at rest)1,805 kcal
TDEE (maintenance)2,798 kcal
Target (maintain)2,798 kcal

Macro split

Protein

151g

22%

Carbs

374g

53%

Fat

78g

25%

Protein is set at 1.8 g per kg of bodyweight — the middle of the ISSN range of 1.4–2.0 g/kg/day for exercising adults. Fat starts at 25% of calories and carbohydrate takes the rest, held at or above the DRI floors of 45% of energy and 130 g/day.

Keeping the number steady is a training problem

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How this is calculated

Three steps, and only the first has a primary source. Resting metabolism comes from the Mifflin–St Jeor equation — men: 10 × kg + 6.25 × cm − 5 × age + 5; women: the same, minus 161. That figure is multiplied by an activity factor to get your total daily expenditure, then scaled by your goal. Protein is set from your bodyweight, fat starts at a quarter of your calories, and carbohydrate takes the remainder.

  1. 01Calculate resting energy expenditure from your sex, weight, height and age using Mifflin–St Jeor (1990).
  2. 02Multiply by an activity factor from the 1.2-to-1.9 ladder to estimate total daily energy expenditure.
  3. 03Scale that by the goal: 0.80 to lose, 1.00 to maintain, 1.10 to build. Then apply a safety floor — we will not display a target below 1,200 kcal/day for women or 1,500 for men.
  4. 04Set protein from bodyweight inside the ISSN 1.4–2.0 g/kg/day range, hold it under the DRI ceiling of 35% of energy, start fat at 25% of calories, and give the rest to carbohydrate — checking that carbohydrate clears both the 45%-of-energy AMDR floor and the 130 g/day RDA.

EstimateEvery number here is an estimate. Mifflin–St Jeor is a population regression: roughly a third of people fall more than 10% either side of their predicted resting metabolism. Weigh yourself over two to three weeks and adjust from what actually happens, not from this page.

What this assumes

  • · You are a healthy adult between 18 and 100. The equation was derived on 498 healthy adults aged 19 to 78, so we refuse inputs outside an adult range rather than extrapolate.
  • · The activity ladder (1.2 / 1.375 / 1.55 / 1.725 / 1.9) has no primary source. We could not find a peer-reviewed paper or health agency that defines it, and it is not part of the Mifflin–St Jeor paper. The authoritative framework, NASEM’s Dietary Reference Intakes for Energy (2023), uses physical activity level bands of inactive 1.0–1.53, low active 1.53–1.69, active 1.69–1.85 and very active 1.85–2.5 — against which our two lowest rungs both fall inside "inactive". Treat this step as the largest source of error here.
  • · The goal factors of 0.80 and 1.10 are our own convention, not a guideline. The 2013 AHA/ACC/TOS guideline instead prescribes an absolute deficit of 500 or 750 kcal/day, or absolute targets of 1,200–1,500 kcal/day for women and 1,500–1,800 for men, as part of a comprehensive programme.
  • · Protein is per kilogram of total bodyweight. The often-quoted 2.3–3.1 g/kg figure for dieting is stated by its source per kilogram of LEAN body mass, for resistance-trained bodybuilders in contest prep — applying it to total bodyweight, as this tool used to, over-prescribes badly at higher body-fat levels.
  • · It cannot account for pregnancy, breastfeeding, a history of eating disorders, diabetes, thyroid disease, or any medication that affects appetite or metabolism.

Sources

  1. [1]Mifflin, M.D., St Jeor, S.T. et al. (1990). A new predictive equation for resting energy expenditure in healthy individuals. Am J Clin Nutr 51(2):241–247 — the BMR equation, derived on 498 healthy adults aged 19–78
  2. [2]NASEM (2023). Dietary Reference Intakes for Energy, Chapter 7 — the authoritative physical activity level bands, against which our activity ladder is a convention
  3. [3]NASEM (2024). Rethinking the Acceptable Macronutrient Distribution Range, Table 3-1 — adult AMDR: protein 10–35%, carbohydrate 45–65%, fat 20–35% of energy
  4. [4]Phillips, S.M., Chevalier, S., Leidy, H.J. (2017). Optimizing protein intake in adults. Adv Nutr 8(2):266–275 — protein RDA 0.80 g/kg/day, protein AMDR 10–35% of energy, and no upper limit set for protein
  5. [5]ODPHP / Dietary Guidelines for Americans — Nutritional goals for each age-sex group (Table E3.1.A4) — the federal reproduction of the adult AMDRs and the 130 g/day carbohydrate RDA
  6. [6]Jäger, R. et al. (2017). ISSN Position Stand: Protein and Exercise. J Int Soc Sports Nutr 14:20 — 1.4–2.0 g protein/kg bodyweight/day for exercising adults — the range our protein target sits in
  7. [7]Helms, E.R., Aragon, A.A., Fitschen, P.J. (2014). Evidence-based recommendations for natural bodybuilding contest preparation. J Int Soc Sports Nutr 11:20 — the 2.3–3.1 g/kg figure is per kg of LEAN body mass, for trained bodybuilders — not per kg of bodyweight
  8. [8]Jensen, M.D. et al. (2013). AHA/ACC/TOS Guideline for the Management of Overweight and Obesity in Adults. Circulation 129(25 Suppl 2):S102–S138 — the 1,200–1,500 (women) / 1,500–1,800 (men) kcal/day prescribed bands, and the under-800 kcal/day medical-supervision rule
  9. [9]NIDDK (NIH). Very low-calorie diet — defines a VLCD as about 800 kcal/day or less, supervised by a health professional

Last reviewed October 2026

This is not medical or dietary advice

Exercise Legend is not a medical authority. This calculator is an estimate for healthy adults and it does not know anything about your health history. Diets under 800 kcal/day are clinically defined as very-low-calorie diets and should only be followed under medical supervision.

If you are planning a deficit, pregnant or breastfeeding, managing a health condition, or have any history of disordered eating, talk to a doctor or a registered dietitian before changing what you eat.